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Lennox G50 wont ignite. Pressure switch is ok, intake clear, exhaust clear too

6K views 43 replies 8 participants last post by  Muzzle127 
#1 ·
I have been trying to fix this problem for 2 days. Here is the sequence. Demand for heat. Small fan turns for a couple seconds, pauses then runs again. I believe the ignitor is supposed to heat during this. Ignitor never heats and fan turns off. Stays off for a couple minutes and then repeats sequence. I tried cleaning ignitor with emery cloth but it wasn't that dirty. Still no heat. Board shows slow flashing right LED. Suggestions??
 
#26 ·
Got up in attic at lunch. Bypassed pressure switch w alligator clip and the ignitor heated and burner fired. So the ID motor is suspect again.

I checked the port on ID and put a paper clip in there. No blockages found. I also again pulled the B vent off the furnace side just to see if theres a blockage on outlet side in the pipe going to roof. The pressure switch still wouldnt close. Next I will remove the ID motor from the furnace and inspect. Just 3 nuts to take off.
 
#29 ·
Removed Id motor and found the felt gasket between furnace and motor in pieces. I think a piece got sucked over exhaust hole. This would explain no draw or exhaust. Possibly the air coming from the side of the fan too next steps are to test motor with straight 120 v from extension chord. Tomorow i will buy a new felt gasket.
 
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